This application claims the priority of German Application 10209008.4 filed Feb. 26, 2002, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a support for a combing means for an opening roller, comprising an opening means designed as a saw-toothed-shaped helix having multiple thread grooves.
A support for a combing means of this type is prior art in German published patent application 19 39 683 (corresponding GB 1234327). The known support is affixed to a base body of the opening roller in a way in which it can be exchanged, and comprises a saw-toothed-like combing means, which is cut out of the metal in one piece. Thus saw teeth occur which are formed on the one hand by grooves extending helix-like, and on the other hand by recesses which extend diagonally thereto. The combing means in the form of a helix can have multiple thread grooves. The known publication does not, however, cite any criteria for the threads.
Opening rollers are applied first and foremost in open-end spinning machines and comprise today supports for combing means whose outer circumference measures in practice between 60 and 80 mm. In modern spinning aggregates, the fiber speed increases from zero at the combing zone to approximately 15 m per second at an area where the opened single fibers leave the opening means and are fed to a twisting device, for example an open-end spinning rotor. The standard average peripheral speed for opening rollers lies today in the range of 25 m per second. This means that the opening means has a significantly higher peripheral speed than the speed of the single fibers at the place where they leave the opening means. As the speed of the single fibers is largely dependent on the air current rotating with the opening roller, it would be desirable if the opening roller were to rotate slower than is usual. This, however, would reduce the combing performance.
In principle, a helix-shaped opening means having multiple thread grooves could provide a solution, because during one rotation of the opening roller, a plurality of teeth would be involved at one and the same combing place. This, unfortunately, means that because of the plurality of threads of the opening means, the angle of inclination of the helix would have to be increased, which renders the combing means much more aggressive and as a result causes damage to the fiber material to be opened.
It is an object of the present invention to find a compromise solution for the contradictory requirements mentioned above. On the one hand, the speed of the opening roller should be reduced by means of a plurality of threads, while on the other hand the aggressiveness of the combing means should be held at acceptable levels.
This object has been achieved in accordance with the present invention in that the number of threads amounts to between one twentieth and one thirtieth of the outer diameter (measured in millimeters) and that the angle of inclination (measured in degrees) of the helix amounts to between 0.5 to 0.7 times the number of threads. Caution should also be taken that the angle of inclination of the helix does not, if possible, exceed 2.5xc2x0.
The compromise solution devised by the applicant applies to fiber lengths, which if possible do not overly exceed 40 mm, as well as to opening rollers, whose outer diameter of the combing means lies in the standard modern range of between 40 to 60 mm. With an outer diameter of, for example, 60 mm, the compromise involves two to three threads, while at an outer diameter of, for example, 80 mm, the range is three to four threads. The above mentioned rules for calculation are to be so understood in that the number of threads is to be chosen which is nearest to the calculated value. As a rule, the empirical formula will result in fractions, which are then rounded up or down accordingly. The rules of calculation also take into consideration the fact that the helix-shaped extending saw teeth rows should have a groove width between them which measures 2 mm, measured at the tooth tips.
These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings.